Volume 50 | Number 5 | October 2015

Abstract List

Brent K. Hollenbeck M.D., M.S., Rodney L. Dunn M.S., Anne M. Suskind M.D., M.S., Seth A. Strope M.D., M.P.H., Yun Zhang Ph.D., John M. Hollingsworth M.D., M.S.


To assess the impact of ambulatory surgery centers () on rates of hospital‐based outpatient procedures and adverse events.

Data Sources

Twenty percent national sample of Medicare beneficiaries.

Study Design

A retrospective study of beneficiaries undergoing outpatient surgery between 2001 and 2010. Health care markets were sorted into three groups—those with s, those without ASCs, and those where one opened for the first time. Generalized linear mixed models were used to assess the impact of opening on rates of hospital‐based outpatient surgery, perioperative mortality, and hospital admission.

Principal Findings

Adjusted hospital‐based outpatient surgery rates declined by 7 percent, or from 2,333 to 2,163 procedures per 10,000 beneficiaries, in markets where an opened for the first time ( < .001 for test between slopes). Within these markets, procedure use at s outpaced the decline observed in the hospital setting. Perioperative mortality and admission rates remained flat after opening (both  > .4 for test between slopes).


The opening of an in a Hospital Service Area resulted in a decline in hospital‐based outpatient surgery without increasing mortality or admission. In markets where facilities opened, procedure growth at s was greater than the decline in outpatient surgery use at their respective hospitals.